1. Field of the Invention
The present invention relates to a binocular having two bodies and a bridge joining the bodies and, more specifically, to such a binocular in which the two bodies each have a row of knuckles respectively pivoted to the respective knuckles at two sides of the bridge.
2. Description of the Related Art
A regular binocular, as shown in FIG. 1, is generally comprised of two bodies 2 and a bridge 1 joining the bodies 2. The bodies 2 each comprise a coupling block 20 respectively coupled to the bridge 1. The bridge 1 comprises two front recessed portions and two rear recessed portions. The coupling block 20 of each body 2 comprises a screw hole 204 disposed at the front side, and a recessed portion disposed near the rear side and aimed at the screw hole 204. Two first steel balls 12 are respectively mounted in the recessed portions of the coupling blocks 20 of the bodies 2 and the rear recessed portions of the bridge 1. Two second steel balls 14 are respectively mounted in the front recessed portions of the bridge 1 and aimed at the screw holes 204 of the coupling blocks 20 of the bodies 2. Two holding down screws 22 are respectively threaded into the screw holes 204 of the coupling blocks 20 of the bodies 2 to hold down the second steel balls 14 in the front recessed portions of the bridge 1. When assembled, the bodies 2 can be turned relative to the bridge 1 to adjust their angular position. The binocular further comprises a central focusing wheel 16 revolvably mounted in the bridge 1, a screw rod 18 threaded into the central focusing wheel 16 and disposed between and in parallel to the bodies 2, and a connecting block 19 fixedly fastened to the screw rod 18 and connected between the lens systems 24 of the bodies 2. When rotating the central focusing wheel 16, the screw rod 18 is driven to move the connecting block 19 forwards or backwards relative to the central focusing wheel 16, and therefore the lens systems 24 of the bodies 2 are moved with the connecting block 19 axially in the bodies 2 to adjust the focusing of the binocular. According to this design, the contact area between the bridge 1 and the coupling blocks 20 of the bodies 2 is limited to few points (the steel balls), i.e., the steel balls 12 and 14 and the holding down screws 22 support the whole gravity of the binocular. When the binocular receives an impact, the connecting area between the bridge 1 and the coupling blocks 20 of the bodies 2 tend to be broken. In order to eliminate this problem, the coupling blocks 20 of the bodies 2 and the bridge 1 must be made of material of high structural strength. However, the use of high structural strength material greatly increases the cost of the binocular. Further, the processing of the recessed portions of the bridge and the coupling blocks of the bodies requires high precision, and the steel balls may fall out of the recessed portions during installation. Because the complicated processing and installation procedure consumes much time and labor, the manufacturing cost of this structure of binoculars is high.